The present invention is directed to a method and apparatus for making a draw tape bag and particularly to a draw tape bag formed of a plastic bag material and having a plastic draw tape in the open end for closing the bag.
Draw string bags have been produced for many years in which a cloth or plastic bag member is formed with an upper encircling hem having oppositely extendable draw strings secured within the hem for closing of the bag. More recently, draw tape bags have been provided including a plastic bag having an upper hem portion. Plastic tape members are located within the hem portion and exposed through openings in the hem to provide a corresponding draw tape bag structure. For example, U.S. Pat. No. 3,772,968 which issued Nov. 20, 1973 discloses a draw tape bag in which a pair of offset draw tapes are located within the common hem. The draw tapes are exposed to the opposite sides of the bag with each exposed draw tape sealed to the bag on a diagrammetrically opposite side. Pulling on the draw tapes thus provides for collapsing of the bag opening.
U.S. Pat. No. 4,624,654 which issued Nov. 25, 1986 discloses a draw tape bag formed from a continuous web which is folded on itself to form the opposite sides of the bag. The aligned free edges are folded inwardly on themselves to form a hem structure. The hems are edges notched at locations corresponding to the sides of the bag between sealed side edges. A draw tape is continuously fed into the open hems, with the inner edges of the hem subsequently heat sealed to complete the hem with the draw tape secured therein. The web is then sealed in longitudinally spaced transverse areas to define heat sealed sides of the bag. The web is severed along the side seals to separate the individual bags. Although such system provides a method of mass producing of such draw tapes bags, the hem portions of the folded web are located in overlapping relationship. The sealing of the edges to form the seam require special apparatus and machinery to prevent sealing of the hems to each other in the closing of the open hems of the bag. Generally, a barrier device is employed to maintain the hems separated from each other during the formation of the bag. The above '654 patent discloses a particularly form of a strip member interposed between the hems during the edges sealing. A similar method of forming a bag is disclosed in U.S. Pat. No. 4,664,649 which issued on May 12, 1987. In this patent, a special barrier is again interposed between the hems during the hems sealing to isolate and separate the hems from each other.